How can I make animations look more natural?
I would suggest that you study the 12 principles of animation closely. Looking at your animations, it's obvious you're not following these; for instance, the ease in, ease out rule. Your camera motions seem to abrupt, too stable. Too unnatural.

And then practice. A lot.

I also recommend the principles of animation series by Dan Floyd from Extra Credits/Play on Youtube, where he covers these principles and show some great implementation of these in games.

You may also want to take some classes in animation, such as Animation Mentor. Keep in mind that any class about animation, even if about traditional drawn animation, will help you master 3D animation.